External hard drive folders not viewable from Macbook air

I have a mid 2009 Macbook air, and recently purchased a 1TB Seegate external hard drive. I reformatted the drive for Mac and backed up my files but cannot see the folders, to confirm that all my pics are there. I am a new Mac owner and don't know a lot about how to navigate the drives. On Windows I used Windows Explorer to see the folders but on my Macbook air, I have not found an equivalent tool to see the folders and pics.
(I am a Canadian visiting Spain and taking pics daily and my Mac hard drive is full and won't let me download any more pics, and my camera disk is almost most full. I can buy a new memory disk for the camera, but I just spent $140 on the external hard drive to avoid this.)
Thanks for any help you can offer.

Did you see the icon of the external hd on the desktop ?
If not Finder > Preference> General >check HD option
Put you're mouse pointer on external hd icon click on wright of the mouse and than option open